CN110650680B

CN110650680B - Device for monitoring blood and respiratory flow

Info

Publication number: CN110650680B
Application number: CN201780078235.4A
Authority: CN
Inventors: 菲利普·兰格; 乔瓦尼·阿莫罗索; 戴维·劳伦斯·坎普; 加布里埃尔·布蒂诺尔; 格里特·德弗里斯
Original assignee: Ida Health Co ltd
Current assignee: Ida Health Co ltd
Priority date: 2016-12-21
Filing date: 2017-11-21
Publication date: 2023-11-07
Anticipated expiration: 2037-11-21
Also published as: EP3558106A1; CN110650680A; JP2022120192A; BE1024423B1; WO2018114180A1; JP2020513892A; JP7093777B2; US11426083B2; US20200093378A1

Abstract

The present invention relates to the field of blood and respiration monitoring technology and provides a non-invasive device for monitoring blood flow of a body member. The device of the present invention is a non-invasive device for monitoring the blood flow and/or respiratory cycle of a human or animal body, comprising: at least one conductive elastomer segment having a variable resistance arranged to extend over the periphery of the body element and being sensitive to the length of the periphery of the body element; means for capturing said length through said variable resistor and providing a signal representative of said length, and means for processing said signal comprising means for extracting a blood flow parameter to be measured. The invention can accurately monitor the artery function in real time during the surgical operation and in the postoperative wound compression stage, and has simple, independent and compact structure.

Description

Device for monitoring blood and respiratory flow

Technical Field

The present invention relates to the field of blood and respiration monitoring technology, and relates to a device for monitoring blood and respiration flow, in particular to a non-invasive device for monitoring blood flow of a body member.

Background

Plethysmography, developed at the beginning of the twentieth century, has made it possible to measure volumetric changes in organs or whole bodies of humans or animals, and has been used to measure peripheral or surface blood flow. In particular, the last 40 th 20 th century, R J Whitney, developed a deformation measurement system with a double lead formed of a rubber housing containing mercury (J Physiol, l21,1-27,1953). The technology was improved later. Various techniques have been found, for example, using photosensors to illuminate the arteries of the wrist to measure changes in arterial volume and thereby generate electrical signals which can then be analyzed by various methods to obtain hematology information. An overview of the plethysmographic method can be found on the Internet (http:// level1diagnostics. Com/research/P/L1D-pulseWavemonograph. Pdf). However, despite being very simple and practical to use, currently available plethysmography techniques still have shortcomings in terms of accuracy.

The development of blood pressure meters (commonly known as tensiometers) has led to the progressive abandonment of the use of plethysmography. The tensiometer is based on the principle of a manometer, which records the arterial response when subjected to both heart pressure and air pressure generated by the device. While tensiometers give less accurate results in a shorter time than plethysmography, they are employed because of their simplicity of use in doctor surgery. However, it only allows an approximate assessment of the pressure representing the blood flow in a short time.

Meanwhile, electrocardiography has become the examination of choice for cardiologists to express cardiac electrical activity. However, this examination requires placing a plurality of electrodes at different locations of the body, which electrodes are connected to an analysis unit to monitor the acquired signals.

Doppler ultrasonography is also used to detect intracardiac and intravascular blood flow. The practitioner moves the sensor along the organ to be analyzed to determine the direction and speed of blood flow. However, this examination is not suitable for long-term use and requires active handling by the practitioner.

Cardiovascular disease is a leading cause of death worldwide. Over the last three decades, research has made it possible to develop a number of drug therapies for certain heart diseases. At the same time, surgical techniques have been significantly improved, particularly by being prone to the installation of arterial support devices such as transluminal coronary stents, which can minimize open heart surgery.

In the face of an increase in the number of procedures to install such devices, legislation allows an increase in the number of practitioners able to perform this operation, previously reserved only for cardiac surgeons. Such an increase in the number of procedures is also accompanied by an increase in the number of post-operative problems.

It has been shown that the respiratory cycle, i.e. the number of inspiration and expiration per time unit, also has an effect on the blood flow.

In particular, a common complication is post-operative stenosis or even occlusion (stenosis) of the artery in which the medical device is implanted, rendering further surgery through the same artery ineffective or even dangerous. However, it is not uncommon for the same patient to need to perform the same type of procedure multiple times during his lifetime. This problem is described in more detail by Muhammad Rashid et al (J Am Heart assoc.2016; doi: 10.1161/JAHA.115.002686). One of the possible reasons for explaining such arterial occlusion/stenosis is the inadequate time and pressure for the compression procedure to be performed on the wound created by the arteriotomy at the beginning of the procedure. Proper compression may actually reduce the risk of occlusion, as described in chapter http:// www.invasivecardiolgy.com/characters-art-transmission-compression-interfacing-radial-art-patent-thermo-stasis-ultra-noise. Currently, there is no technique for monitoring arterial function in the wound environment during surgery or during compression of the wound after interventional therapy, and not to mention ultrasound monitoring, which is impractical to implement in such situations.

Thus, there is currently a lack of a simple, self-contained and compact device that can accurately monitor arterial function in real-time during surgery and during the post-operative wound compression phase. Such monitoring enables the practitioner to adjust his skill and the pressure applied to the wound in real time to minimize the risk of post-operative problems such as arterial occlusion.

This is the problem addressed by the present invention. The present invention proposes an improvement to plethysmography techniques, advantageously using advanced techniques in the field of conductive materials.

Heeger, macDiarmid and Shirawa have shown that non-conductive polymers can be "doped" to promote electron movement along the conjugated double bonds of the polymer and render the polymer conductive. Document WO 2015/049067 details a method of doping polymers, in particular elastomers, with nanomaterials, in particular carbon-based nanomaterials of the graphene type, in order to render these polymers conductive. These conductive elastomers have a resistance that varies with length (i.e., the stress applied thereto). This is described in detail in the above-mentioned patent document, which suggests using this property to measure subtle physiological movements, such as pulse or respiration.

The present invention relates to a non-invasive plethysmographic device comprising an electrically conductive elastomer with variable resistance, which can be used in particular in operating rooms without causing any problems for medical practitioners.

Disclosure of Invention

In view of the problems of the prior art, the present invention provides a non-invasive device for monitoring blood flow of a body member that is capable of accurately monitoring arterial function in real time during surgery and in the post-operative wound compression stage, and is simple, independent, and compact in structure.

The technical scheme of the invention is as follows:

a non-invasive device for monitoring blood flow of a body element, the body element comprising a network of channels through which the blood flow flows, characterized by: comprising

-at least one conductive elastomer segment with a variable resistance arranged to extend over the periphery of the body element and being sensitive to the length of the periphery of the body element;

-means for capturing said length by means of said variable resistor and providing a signal representative of said length, and

-means for processing said signals comprising means for extracting blood flow parameters to be measured.

The invention also relates to a non-invasive device for monitoring the respiratory cycle of the human or animal body that causes a change in the outer circumference of a body element, characterized in that: comprising

-at least one conductive elastomer segment with a variable resistance arranged to extend along the periphery of the body element and being sensitive to the length of the periphery of said body element;

-means for processing said signals comprising means for extracting the respiratory cycle parameters to be measured.

The applicant therefore starts from document WO 2015/049067 for solving the above problems. However, this document does not describe the use of conductive elastomers with variable resistance in plethysmographic devices, and is therefore legally excluded from the field of the prior art. By reading this document, in particular the paragraph relating to the sensor (page 24, lines 24-33), the person skilled in the art is faced with a wide range of possibilities for using such a sensor, and cannot be led to specific embodiments of plethysmographic devices using conductive elastomers with variable resistance.

The blood flow corresponds to the blood flow in blood vessels and the heart. Blood vessels are all conduits that convey blood, including arteries, veins, venules, and capillaries.

A non-invasive monitoring device is a device capable of monitoring one or more parameters without any invasive procedure to the skin. It is generally accepted that simple blood sampling and product injection are also non-invasive. The non-invasive nature of a piece of equipment generally means that there is no risk.

In a preferred embodiment, the conductive elastomer segment with variable resistance is arranged around the body element and is sensitive to the length of the outer periphery of said body element.

In a further advantageous embodiment, the conductive elastomer segments with variable resistance are fixed to the adhesive.

In any case, the conductive elastomer is obviously in direct contact with the skin. Placing the elastomer on a skin-covering fabric, such as clothing, can significantly reduce the sensitivity of the device.

Herein, a body element refers to any portion of the body that can be wholly or partially covered or surrounded by the elastomeric section. These body elements may include the lungs, torso, or throat. They may belong to humans or animals.

The periphery of a body member refers to the line that forms the boundary of the surface of the member. The elastomeric section may extend over a portion of, for example, the torso or neck. The length of the outer circumference may be only a portion of the length of the outer circumference of the body member. In addition, "around the limb" does not necessarily mean that the elastomeric section is closed around the limb itself, as the capturing means and the handling means are arranged around the limb. The terms "turn" and "periphery" will be used indifferently in the remainder of this document.

An adhesive means here a thin layer of polymer tissue or any other suitable material, covered on at least one of its faces with an adhesive or cohesive substance, so that the adhesive is able to permanently adhere to the skin at the body element where it is located. Such adhesive sheets are particularly useful on dressings or what is commonly referred to as a patch.

In a preferred embodiment of the invention, the means for capturing said length comprise at least one measuring bridge, wherein at least one resistor is formed by an electrically conductive elastomer with a variable resistance. The electrical signal output from the measuring bridge is an image of the length of the outer perimeter.

The measuring bridge here represents an electronic component comprising at least one resistor, the value of which varies according to the parameter to be measured (here length). A well known example of a measuring bridge is a wheatstone bridge, but there are also many variants, such as an ac bridge, a euro bridge, a cilin bridge and a robinson bridge, which can improve the measuring accuracy.

The change in length of the conductive elastomer, i.e. the change in the length of the outer circumference of the body member to be monitored, results in a change in the resistance of the conductive elastomer, which is evaluated by the measuring bridge and is shown as an image of the blood flow at the member surrounded by the conductive elastomer. The principle of a wheatstone bridge is well known to those skilled in the art. Its use in deformation gauges is widely documented (distinction between operational and instrumentation amplifiers, electronic design, month 8, 26, 2015; signal conditioning wheatstone resistance bridge sensor, texas instruments, application report SLOA034, 9, 1999). As a general rule, the measuring bridge here performs the function of an electronic amplifier and can be an operational, differential or instrumentation amplifier. The measuring bridge may also be referred to as a measuring circuit, the bridging concept being associated with the presence of a variable-resistance conductive elastomer.

In an advantageous embodiment of the invention, the processing means is electronic means and the means for extracting parameters of the blood flow to be monitored comprise an algorithm arranged to receive information about said length in order to extract parameters of the blood flow to be monitored therefrom.

BioMedical Engineering OnLine,20054:48 Such an algorithm is described in (DOI: 10.1186/1475-925X-4-48). They can in particular separate information relating to arterial blood flow from information relating to venous patterns and/or respiratory cycles. They can also analyze the relationship between the two streams.

The beneficial effects of the invention are as follows:

the invention enables real-time accurate monitoring of arterial function without any problems for medical practitioners by providing a conductive elastomer segment with a variable resistor sensitive to the peripheral length of the body element, means for capturing the peripheral length of the body element by the variable resistor and providing a signal representative of the length, means for processing the signal, enabling real-time extraction of blood flow parameters to be measured and respiratory cycle parameters to be measured during surgery and in the post-operative wound compression phase.

Drawings

FIG. 1 is a schematic diagram of an apparatus for monitoring blood flow according to the present invention;

fig. 2 is a schematic view of the apparatus of fig. 1 around a patient's wrist;

FIG. 3 is a detailed schematic diagram of the capture and process cartridge of the apparatus of FIG. 1;

fig. 4 is another embodiment of the apparatus for monitoring blood flow of the present invention including a plurality of conductive elastomer segments and positioned about a patient's wrist;

FIG. 5 is a schematic illustration of the placement of the device of FIG. 5 inside the wrist with respect to incisions made in the wrist artery and radial artery;

fig. 6 is another embodiment of the apparatus for monitoring blood flow of the present invention comprising two conductive elastomer segments and positioned about a wrist of a patient;

FIG. 7 is a detailed schematic diagram of the capture and process cartridge of the device of FIG. 7;

FIG. 8 is a schematic representation of one form of the conductive elastomer segment of the present invention;

FIGS. 9a and 9b illustrate another embodiment of the apparatus for monitoring blood flow of the present invention, including a system for adjusting the length of a variable elastomer segment;

FIG. 10 is a schematic illustration of one particular construction of a conductive elastomer segment;

FIG. 11 is a schematic diagram of a possible use of the apparatus of the present invention;

FIG. 12 is a schematic view of the apparatus of the present invention integrated into an adhesive;

FIG. 13 is a schematic diagram of an algorithm of the apparatus of the present invention;

FIG. 14 is a schematic view of an apparatus of the present invention, including an extension member of the conductive elastomer of the apparatus of the present invention;

FIG. 15 is a schematic view of the apparatus of the present invention associated with an automated compression wristband;

fig. 16 is a schematic view of the device of the present invention integrated into a smart watch wristband.

Detailed Description

The invention will be further described with reference to the drawings and detailed description.

As shown in fig. 1, 2 and 3, the plethysmographic device according to the present invention comprises a wristband 1 carrying a box 2 for capturing and processing signals and an algorithm 3 housed in a data processing system 4, the functions of algorithm 3 being combined with those of the processing means of box 2.

The wristband 1 is here an elastomer section intended to partly surround the wrist 5 and be fixed to the case 2 so as to support the case 2 on the wrist 5. The elastomer section and the box may be connected in a simple standard manner, for example by having a protected trademarkOr in the form of a strap for supporting a watchcase. The wristband 1 is made of a conductive polymer so as to press against the skin of the wrist 5.

The box 2 comprises a wheatstone bridge 6 powered by a power source 7 and having its output connected to a wireless transmitter 8. The wristband 1 is integrated as an unknown resistance in the bridge 6 for evaluation, the wristband 1 being connected to one of the two ends 9 of the diagonal of the bridge 6 where the detector 10 is arranged and to one of the two ends 11 of the diagonal of the bridge 6 where the power supply 7 is connected, the detector 10 being connected to the emitter 8.

The data processing system 4 loading the algorithm 3 comprises a receiver 12, the receiver 12 being arranged to be connected to the transmitter 8 of the cartridge 2. The algorithm 3 thus works in conjunction with the measuring bridge 6, the wireless transmitter 8 and the wireless receiver 12.

A battery or rechargeable battery may be envisaged as the power supply 7.

The connection between the transmitter 8 and the receiver 12 may be a bluetooth or WiFi connection or any other wireless technology.

Computers, touch tablets, smartphones or even connected watches may be considered as data processing systems.

Proper positioning and adjustment of the tension of the conductive elastomer is important to obtain the best quality signal. The length of the elastomer may be adjusted so that the tension of the conductive elastomer is sufficient to detect a change in its length, and thus a change in resistance, but not so great as to not affect blood circulation. The length of the wristband 1 may be adjusted manually or automatically to the wrist circumference.

Having described the structural features of the apparatus of the present invention, the operation thereof will now be described.

During its operation, the length of the conductive elastomer varies according to venous blood flow, arterial blood flow and respiration rate. The bridge 6, comprising the wheatstone type of the wristband 1 made of conductive elastomer, will generate an electrical signal which is an image of these physiological parameters. This signal is then amplified before being sent by the transmitter 8 to the receiver 12 of the data processing system 4 comprising the algorithm 3, so that its various components can be extracted from the received signal.

Algorithm 3 may isolate, among other things, electrical signals related to arterial pulses from electrical signals related to venous blood flow. It may also analyze the difference between the two blood streams and the first or second derivative of the difference between the two blood streams. It may further comprise frequency analysis in order to separate the blood flow more clearly for better signal quality. This information may then be displayed on the screen 13 of the data processing system 4.

The information displayed may be varied and adapted to the environment in which the device of the invention is used. Typically, the physiological parameters calculated by the algorithm 3 as a function of time or their changes in relation to each other will be displayed in a simple manner for the practitioner analysis.

During a surgical procedure intended to introduce stent-like devices, an incision is made in the radial artery at the forearm, for example, through the radial artery. It is then conceivable to position the wristband 1 between the hand and the incision. This can be achieved by the wristband 1 being of small dimensions, the wristband 1 being not bulky and not comprising any electrical connectors that might interfere with the work of the practitioner. The practitioner can then monitor arterial and venous blood flow at the wrist in real time during introduction of the stent and adjust its operation accordingly. Likewise, after the end of the procedure, the practitioner will apply pressure to the wound created by the arteriotomy in order to stop bleeding. By being able to monitor arterial and venous blood flow in real time, a medical practitioner is able to adjust the pressure applied to the wound.

In the case shown in fig. 15, where the wound compression phase would be defined by, for example, terumo TR(http:// www.medicalexpo.fr/prod/terumo-medical/product-71204-454828.html) The provision of automatic wound compression means 14 management, it is conceivable that the pressure exerted by the automatic compression means is controlled wirelessly by an additional algorithm integrated in the data processing system 4, as a function of the analysis of the data provided by the wristband 1. The medical compression device may be connected to the data processing system wirelessly or, as the case may be, by direct wired connection to the wristband case. Different types of compression may be applied and controlled by directly and/or wirelessly connected measuring devices. The compression may be performed, for example, by pressure from an external element (e.g., a hard or soft ball, an air chamber or a chamber containing an optionally compressible fluid).

The correct positioning and adjustment of the tension of the elastomer section 1 is important for the measured signal quality and the quality of the parameters subsequently extracted by the detection and analysis algorithm. The operator can easily place the wristband on the wrist, near the hand, but not in a position that would interfere with the surgical procedure. The complex adjustments then mainly consist in tightening the wristband to adjust its compression or tension. This is controlled by adjusting the length of the conductive elastomer band to an optimal force or tension at which the elastomer remains sufficiently flexible but not too relaxed. It is important to note that absolute forces on the elastomer do not affect the measurement, but do affect its accuracy. This is related to the physical properties of the elastomer, such as its modulus of elasticity, temperature and size. The elastomer may be manufactured in a specific form so that it is more flexible, which means that it will provide a higher degree of precision and that its length will be easier to adjust.

By using a locking system cooperating with the conductive elastomer segments, the length of the elastomer can be advantageously adjusted. To facilitate this fit, the conductive elastomeric strip 1 may include a continuous material 110 composition having a particular relief, such as the repeating relief 111 shown in fig. 8. Wherein the relief is a rounded rectangular shaped perforation. But the relief may take any form compatible with the strength, precision, flexibility and resistance required by the wristband 1. For example, the relief may be a snap-in mode, such as used on a clamping collar. This embodiment also improves the electrical contact between the conductive elastomer and the mechanical parts of the electronic components connected to the box 2.

Likewise, when mounted on the wrist, the adjustment of the wristband 1 may also be controlled by another algorithm integrated in the data processing system 4, the driving means making it possible to tighten the conductive elastomer to its optimal tension for monitoring, according to an analysis of the data provided by the wristband 1.

Referring to fig. 9a and 9b, the skin 311 of the wrist 310 is surrounded by a conductive elastomer section 313 and a box 312 containing the electronics of the device and a clamping member 316. The clamping member 316 comprises a motor 315, which motor 315 can move the conductive elastomer segment at its end 313B by means of a clamping ring 314, thereby adjusting its length, the other end 313B being fixed to the cassette 312. The motor 315 may be controlled by the data processing system 4 and tension or relax the elastomeric section 313 to its optimal tension. The tension is proportional to the electrical resistance of the elastomer and can be extracted from the electrical signal generated by the device. It is contemplated that the end of the conditioning operation may be signaled to the operator, for example by a visible light signal on the box 2, a message on the screen 13 of the data processing system 4, a sound signal emitted by the box 2 or the data processing system 4, a vibration of an element of the device or a combination of a plurality of these signals.

An advantageous application of the invention is the simultaneous use of a plurality of watchbands 1. A second wristband may be placed between the elbow and shoulder to generate a second electronic signal that may be analyzed with respect to the first electronic signal and provide the practitioner with all additional information about the arm's blood flow. In a similar manner, one or more watchbands may be symmetrically arranged on the second arm in order to obtain a so-called "reference" signal, with respect to which the blood flow of the arm undergoing the operation can be compared.

Referring to fig. 4 and 5, the non-invasive plethysmographic monitoring device of the present invention may include two conductive elastomer segments disposed around the body member.

The two conductive elastomer segments 101a and 101b are each connected by one end to the box 102a and by their other end to the box 102b and partly around the wrist 5. The two cassettes 102a and 102b are each constructed in a similar manner to the previously described apparatus. When the wristband is installed, a first cassette 102a is placed between radial artery 15 and ulnar artery 16 and a second cassette 102b is placed on top of the wrist. In this configuration, the change in length of the conductive elastomer segment 101a is related to the radial artery 15 and the change in length of the conductive elastomer segment 101b is related to the ulnar artery 16. This configuration makes it possible to obtain two separate electrical signals sent by the wireless communication units of boxes 102a and 102b to data processing unit 4, which data processing unit 4 comprises algorithm 3 capable of processing these signals in order to extract therefrom blood flow parameters, which enables the practitioner to obtain more accurately the information about each artery separately. In particular, if he makes an incision 17 in the radial artery, he can compare the blood flow of the two arteries on the wrist and adjust his surgery if necessary. A wheatstone bridge circuit is used here, but it is obvious that any suitable analog system known to a person skilled in the art that can convert the length information of the elastomer segments into current and/or digital information, such as other forms of measuring circuits or amplifiers, in particular differential amplifiers, is also conceivable.

Referring to fig. 6 and 7, an alternative variation for analyzing signals related to the ulnar artery 16 and radial artery 15, respectively, is to use two conductive elastomer segments 201a and 201b. Each of which is connected by one end to the box 202 and by its other end to the fixation element 218 and partly around the wrist 5. In this case, the box 202 comprises two wheatstone bridges 206a and 206b, each comprising one of two elastomer segments 201a and 201b, respectively, as unknown resistances. Since each end of the elastomer must be connected to a wheatstone bridge for proper operation, two wires 219a and 219b need to be added to complete the loop formed by the elastomer segments 201a and 201b, respectively, in their respective wheatstone bridges. These wheatstone bridges are connected to a detector 210a and 210b, respectively, and to both emitter 208 and power supply 207. Similar arrangements with three or more elastomer segments, each comprised in one measuring bridge, but all connected to the same emitter, are conceivable.

Also, the use of the device of the present invention is not limited to the wrist or arm; it can also be used for other components or organs according to the needs of the practitioner; for example, when the stent is assembled through the femoral artery, the wristband may be placed on the thigh.

The use of the present invention is not limited to use during surgery. It may be applied to monitor blood flow and/or any other activity of the respiratory cycle.

Taking sleep apnea as an example. The patient may then be provided with a device according to the invention in the form of a wristband or patch which is connected during sleep to an analysis perimeter such as the patient's smartphone, which analysis perimeter contains applications for analyzing the signals sent by the electronics of the device and which may emit sound and/or light signals to wake up the patient in case of dangerous apneas of the patient.

Devices for monitoring blood flow and/or respiratory cycle include one or more conductive elastomer segments that can be used in a number of parts of the body. It can be used before, during or after surgery. It may also be used for long periods of time, days, weeks or months to monitor physiological parameters of the patient, such as arterial and/or venous blood flow and his cardiac coherence.

Referring to fig. 10, the device of the present invention may be used on the wrist 1606, ankle 1610 or knee 1609 to monitor venous problems of the leg, on top of the thigh 1607 to monitor the femoral artery, or on the lower portion of the thigh 1608 to detect arterial and/or venous occlusions. It may also be applied to different heights of the upper arms 1603 and 1604 and/or the forearms 1605 and 1606 to detect arterial and/or venous occlusion. It can also be advantageously used to monitor physiological behaviour of the penis to elucidate the type of erectile dysfunction.

Application of the device to the neck 1602 allows monitoring of respiratory rhythms, respiratory cycle instabilities, and arterial and/or venous blood flow to the brain.

Monitoring segments of conductive elastomer may also be mounted on the torso, such as around the waist 1627 to monitor abdominal movements, such as to monitor post-intestinal-surgery abdominal movements, or on the chest 1626 to monitor respiratory cycle, cardiac coherence, and arterial and/or venous heart activity.

Second, the device of the present invention can be arranged aesthetically pleasing as a piece of jewelry so as to be able to be used gracefully, practically and comfortably during the day and night.

Another very useful and novel embodiment of the present invention is to connect one or more conductive elastomer segments and a capturing and/or processing device to the adhesive to form a patch type device.

Referring to fig. 12, a conductive elastomer segment 1621 is coupled to capture device 1620 by an electrical connector 1623. The elastic body 1621 and the catching device 1620 are disposed on the adhesive surface of the adhesive portion 1622, and integrally form a patch 1624. Capture device 1620 includes the same elements as cassette 2 and cassette 202 already described. The patch 1624 may be used, for example, on the chest or abdomen to measure cardiac coherence, respiratory rate, and blood circulation. In particular, the patch may be used to assess whether a patient's breath is deep breathing or only on top of the lungs (incoherent) to indicate the sympathetic or parasympathetic balance of his metabolism. Patch 1624 may also be used to measure bladder function, which is a very important parameter when the patient is in intensive care.

The conductive elastomer segments of the present invention can be manufactured in a "layered" structure to reduce size/production cost and weight while improving sensitivity and measurement accuracy. The multilayer structure is composed of alternating layers of conductive elastomer and non-conductive elastomer. This advantageous configuration allows multiple measurements to be made using only one layering section 1500.

Referring to fig. 10, here an elastomer segment 1500 includes alternating conductive elastomer layers 1501 (a, b, and c) and non-conductive elastomer layers 1502 (a, b, and c), which may have the same or different stiffness values. The conductive elastomer layers 1501a, b, and c may also have different conductive values from one another. These layers 1501a, b and c are connected to the rest of the device by electrical connectors. A non-conductive elastomer layer 1502a advantageously forms the outer layer that will contact the patient's skin to electrically isolate the device.

In one embodiment, all of the conductive layers cover the entire length of the segment 1500.

It is also contemplated that a portion of the conductive layer, here layer 1501b, may be "split," that is, interspersed with non-conductive portions 1503 over its length to form conductive segments 1504,1505, and 1506. Each conductive segment is connected to the rest of the device by a smart arranged electrical connector. This division gives the layer 1501b the nature of a wristband made up of multiple conductive elastomer segments as described above, and may isolate signals from different venous or arterial blood flows, such as those associated with the ulnar artery and radial artery.

The non-conductive portion 1503 may or may not be made of an elastomer and may optionally be made of a different material.

The elastomeric section 1500 may include a plurality of identical conductive layers, each of which produces a signal that may be processed individually or collectively, or by calculating the interaction of signals from similar layers.

In general, the electrical connector may be made of any suitable material, such as two metals, e.g., copper and conductive ink.

One or more superimposed elastomer segments may be used to design a device for specific monitoring. For example, the structure of an elastomeric segment designed for monitoring the femoral artery may be the same as an elastomeric segment designed for monitoring the wrist radial artery, but its dimensions will be adjusted according to the application.

The means for extracting parameters of the blood and/or respiratory flow to be monitored comprise an algorithm using a number of steps to convert the signal measured at the measuring bridge into a signal viewable by the operator.

Referring to fig. 13, in a first step 2001, for each elastomer segment, an electrical signal s, here a voltage v, is measured at time t. The electrical signal includes voltage maxima and minima from which the average heart frequency fc is extracted. For example, for humans, the heart frequency is between 0.25 and 4 hertz. To measure the sampling frequency correctly, i.e. the frequency at which the heart frequency extraction can be performed, 200Hz is sufficient. In practice, the extraction 2002 of the heart frequency fc includes a plurality of steps 2003 to 2011.

In a first step 2003, the signal S is passed through a band-pass filter, i.e. a filter which only allows to pass a frequency band or frequency range lying between the low and high cut-off frequencies of the filter, e.g. a FIR (finite impulse response) filter. From the resulting signal Sf, in a second step 2004, first and second derivatives S ', S' are extracted. In the digital mode, the first and second derivatives are typically calculated from S ' (n) =s (n+1) -S (n) and S "(n) =s ' (n+1) -S ' (n), where n is the number of the sample.

In step 2005, the first derivative S ' is binarized into signal S ' b, the positive value of signal S ' is replaced with 1 and the negative value is replaced with 0. In an independent and/or parallel step 2006, the second derivative is rectified to a signal S "p by setting all negative values to 0.

In a calculation step 2007, the product of the binarized first derivative S' b and the rectified second derivative S "p gives a signal W from which, in step 2008, a maximum Wmax can be identified. In step 2009, a so-called "weighted" digital filter is applied so that components Wmaxf related to the arterial frequency can be extracted from these maxima Wmax. The signal Wmaxf is then processed again to eliminate "noise" therein by bandpass filtering 2010.

The time interval between the two maxima of the arterial pulse signal may then be detected in step 2011 in order to extract the heart frequency therefrom.

From which the heart coherence defined by the heart mathematical study, i.e. the change in heart frequency, can be deduced.

Cardiac coherence is a monitoring that can be analytically compared to the heart beat rate and the previous heart beat. This process is the root cause of the balance of the body's sympathetic and parasympathetic nervous systems. Such monitoring may particularly assess stress levels in a subject and optionally detect the onset of a condition such as burnout, depression or stroke.

In the case of a device comprising a plurality of elastomer segments, the signals corresponding to each elastomer segment are processed separately and each signal goes through all steps 2003 to 2011.

Other parameters of the blood flow and the breathing cycle can also be extracted from the same signal Sf sent out by the band-pass filtering step 2003.

In step 2012, for each elastomer segment, the signal Sf is processed by integrated Fast Fourier Transform (FFT) vibration analysis, i.e. on each frequency band corresponding to an individual physiological parameter, from which the spectral power density PSDi of each frequency group, e.g. the frequency of the venous and arterial systems and the respiratory frequency, is extracted. In fact, each physiological function can be associated with a set of frequencies, which makes it possible to characterize it in terms of its period, energy and dynamics. Then, in step 2013, the signals PDSi obtained for each frequency band may also be weighted by their energy and intensity in order to generate a signal Wi representing each physiological function measured, such as a respiratory signal Wr, a venous signal Wv or an arterial signal Wa.

For each elastomer segment, the frequency band considered may depend on the particular location of the segment on the body element and the primary signals desired for those locations.

In the case of a device comprising a plurality of elastomer segments, the signals Wi obtained for each elastomer segment may be compared in order to automatically detect the type of physiological parameter detected mainly by each elastomer segment.

All of the steps of the algorithm 300 described above are generated in real time by the data processing system and the signals generated thereby are viewable by an operator.

During the steps of the execution of algorithm 300, all measurements, signals, or calculations may be stored in a local or remote non-volatile memory, such as a hard disk or cloud.

The steps of algorithm 300 are detailed herein by way of example. The nature, number and order of steps may obviously be different in order to construct an algorithm so that any information that may be used by a practitioner may be extracted from the length measurement of the variable elastomer segment.

Referring to fig. 14, applicants have surprisingly found that the placement of an extension member, here a bead 404, of static length, inserted into the elastomer section, between the conductive elastomer section 401 attached to the box 402 and the periphery of the wrist 5, particularly at the level of the radial artery 15, can significantly improve the accuracy of the measurement signal associated with the radial artery 15.

In fact, by means of geometrical effects, by slightly separating the elastomer section 402 from the arm 5, the presence of the beads can amplify the length variation due to the radial artery diameter variation, i.e. the amplitude of the signal by increasing its sensitivity.

Beads are used herein. The beads slide over the elastomeric sections, which can be easily moved therein by sliding, and are not easily disengaged therefrom. However, any other positionable rigid element, i.e. adapted to be stably positioned at a specific location of the body member over time, e.g. on an artery to be monitored between skin and elastomer, is conceivable. The element may, for example, have a square, hemispherical shape or any other shape deemed suitable by a person skilled in the art. The rigid element may be made of any suitable material and may be made of wood or plastic, for example.

In the case of a device comprising a plurality of conductive elastomer segments, it is conceivable to install a plurality of extension members, each positionable on an elastomer segment for monitoring a plurality of arteries. For example, an apparatus according to the invention, which comprises two elastomer segments, each covering the entire circumference of the wrist, may comprise an extension member positionable on each elastomer segment. During use, the first extension member will be positioned between the first elastomer segment and the skin at the radial artery and the second extension member will be positioned between the second elastomer segment and the skin at the ulnar artery. Thus, the device can measure information about both arteries very accurately. Other elastomeric segments with extension members may also be added to measure, for example, venous blood flow.

The device according to the invention thus comprises at least one extension member positionable between the conductive elastomer section of the device and the outer periphery of the body element to be monitored, at a point of interest, preferably a channel in which blood flow flows.

It is conceivable to use the extension member for other measurements by integrating miniaturized additional measuring instruments therein. For example, an acoustic or ultrasonic microphone associated with the extension member may enable Doppler measurements of arterial blood flow to be made while plethysmographic measurements are being made. The measurement may be combined with other information generated by the apparatus of the present invention to improve its accuracy, quality and scope.

It has been mentioned above that the signal data processing system may in particular be a smart watch. Referring to fig. 16, a smartwatch 503 is equipped with a connection port 504 at one of the wristband fasteners 506. It is conceivable to integrate the device of the invention, i.e. at least one conductive elastomer segment 501 (here two are shown), and a circuit 502 comprising means for capturing the length of the conductive elastomer segment 501, signal processing means and optionally a battery, in the wristband 501 of the watch 503. Once the signal is processed, it may be sent through the connection port 504 of the watch 503 to a software program or application 506 installed on the watch. The smart watch 503, i.e. adapted to communicate via Wi-Fi, bluetooth or 3G or 4G, may be programmed to automatically notify medical emergency services in case problems related to the subject's blood flow or respiratory cycle are identified. This configuration is particularly suitable for subjects exhibiting a high risk of heart failure or severe lung disease. Emergency services not only can intervene quickly, but also their intervention can be directly adjusted by the information provided by the devices integrated in the patient wristband.

The wristband and device of the invention form an assembly, one of which is adapted to be mechanically connected to a smart watch and the other of which is adapted to be electrically connected to the smart watch.

When used in a wet environment, such as when diving at the sea, the wristband supporting the device of the invention may be coated with silicone to render it waterproof.

The term "smart Watch" is used herein, but should be understood to refer to any Watch-sized portable monitoring system, such as Apple Watch, that integrates different technologies.

The device of the invention may also be used to monitor breathing and/or heart activity of an infant. It is even conceivable to combine it with an infant breathing monitor, such as a sensor pad placed under the mattress. This type of cushion has poor sensitivity which can lead to false alarms. Combining the information recorded by the mat with the information from the wristband of the invention may advantageously increase the overall sensitivity.

Claims

1. A non-invasive device for monitoring the blood flow of a body element, the body element (5) comprising a network of channels through which blood flows, characterized in that: the apparatus includes:

at least one conductive elastomer segment having a variable resistance (1; 101; 201) arranged to extend over the periphery of the body element (5), the variable resistance being sensitive to the length of the periphery of the body element;

an electrically conductive elastomer section with a variable resistance (1; 101; 201) is arranged around a body element (5) and is sensitive to the length of the outer periphery of said body element;

the conductive elastomer section with variable resistance (1; 1500) is a multi-layer section (1500) comprising alternating conductive elastomer layers (1501 a,1501b,1501 c) and non-conductive elastomer layers (1502 a, 150b, 1502 c);

means (2; 102; 202) for capturing said change in length and providing a change signal representative of said length by means of said variable resistor (1; 101; 201), and

means (2, 4) for processing said signals, comprising means for extracting blood flow parameters to be measured;

the means for capturing said length comprise at least one measuring bridge (6), wherein at least one resistance is formed by a conductive elastomer segment with a variable resistance; the electrical signal output from the measuring bridge (6) is an image of the length of the outer periphery.

2. A non-invasive device for monitoring the respiratory cycle of a human or animal body, said respiratory cycle causing a change in the peripheral length of a body member, characterized by: comprising

means (2, 4) for processing said signals, comprising means for extracting respiratory cycle parameters to be measured;

3. The apparatus according to claim 1, wherein: wherein the processing means is an electronic device and the means for extracting blood flow parameters to be monitored comprises an algorithm arranged to receive information about said length in order to extract blood flow parameters to be monitored from the information.

4. The apparatus according to claim 2, characterized in that: wherein the processing means is an electronic device and the means for extracting the respiratory cycle to be monitored comprises an algorithm arranged to receive information about the length, in order to extract parameters of the respiratory cycle to be monitored from the information.

5. The apparatus according to any one of claims 3 or 4, wherein: a conductive elastomer section having a variable resistance (1; 101; 201) is fixed to the adhesive member.

6. The apparatus according to claim 5, wherein: the measuring bridge (6) is connected to a wireless transmitter (8), which wireless transmitter (8) is connected to a wireless receiver (12) of a data processing system (4), which data processing system (4) is arranged to process signals received by the wireless receiver (12).

7. The apparatus according to claim 6, wherein: the algorithm (3) works in conjunction with a measuring bridge (6), a wireless transmitter (8) and a wireless receiver (12).

8. The apparatus according to claim 7, wherein: comprises a plurality of conductive elastomer segments (101 a,101b;201a,201b;1501a,1501b,1501c,1504,1505, 1506).

9. The apparatus as claimed in claim 8, wherein: a cassette (202) is provided, said cassette comprising at least two measuring circuits (206 a,206 b), each measuring circuit comprising one conductive elastomer segment (201 a,201 b).

10. The apparatus according to claim 9, wherein: comprising means (316) for fastening the conductive elastomer segments.

11. The apparatus according to claim 10, wherein: at least one extension member comprising said conductive elastomer section, said extension member being arranged positionable between the conductive elastomer section of the device and the periphery of the body element to be monitored.

12. An assembly comprising an apparatus according to claim 11 and an automatic compression device arranged to be controlled by the apparatus.

13. An assembly comprising the apparatus of claim 11 and a respiration monitoring pad arranged to cooperate with the apparatus.